﻿<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>下拉框实现多选</title>
</head>
<body>
<select name="sel" multiple>
    <option>首都图书馆</option>
    <option>新华书店</option>
    <option>数字图书馆</option>
    <option>图书大厦</option>
    <option>在线图书网</option>
</select>
</body>
</html>